Photographic stripping film



jam, 1945- J. G. CAPSTAFF ET AL 2,367,665

PHOTOGRAPHIC STRIPPING FILM Filed Aug. 7, 1942 -6REE// SENS/T/VEEMULSION.

. CELLULOSE ESTER, WATER SOLUBLE.

m w w E w m 5 m m U L B YELLOW F/L TER LAYER.

RED SENS/T/VE EMULS/O/Y.

LLL/LOSE ESTER, WATER SOLUBLE. GREEN SENS/Tl VE EMULSION.

cfiw A m m Y O Q Y CELLUL 085 E8 TEE, AQUEOUS ORGAN/C 50L VENT ORALKAL/sou/51.5, lNSOL UBLE WATER. RED SENSITIVE EMULSION. SUPPORT.

Patented Jan. 23, 1945 PHOTOGRAPHIC STRIPPING FHM John G. Capstaif, GaleF. Nadeau, and Clemens B. Starch, Rochester, N. Y., assignors to EastmanKodak Company, Rochester, N. Y., a corporation of New Jersey ApplicationAugust 7, 1942, Serial No. 453,960

Claims.

This invention relates to photographic film, and more particularly to aphotographic stripping film, having separable sensitive layers whichcanbe transferred to suitable supports and capable of use in theimbibition process of motion picture color photography.

Stripping films of various types and for diverse purposes have beenknown and used for many years in certain types of still photography.However, to applicants knowledge stripping film of the multilayer typehas not heretofore been suc cessi'ully developed for motion picturework. For such work, at least three new requirements enter that wereabsent from still photography. First, the cementing stripping mediummust stick tightly enough and yet be flexible and resilient enough sothat the film can be passed over numerous pulleys and sprockets withoutthe layers coming apart; second, the emulsion layers must be stripped inaccurate registry with the perforations on their permanent supports; andthird, the very large magnification in the projected pictures makes itmandatory to keep th overall thickness of the sensitive film to aminimum so that sufficient resolving power is achieved.

One object of the present invention is to provide a multilayer strippingfilm comprising in its simplest form a support having on one side atleast two superposed silver halide emulsion layers separated by a layerof colloidal material soluble in aqueous media or at least so softenedthat it will strip readily from one of the emulsion layers.

Another object of the present invention is to provide a multilayerstripping film comprising a support having on one side three superposedsilver halide emulsion layers, the two outer emulsion layers separatedby a layer of colloidal material soluble or at least permeable in anaqueous medium, the inner two emulsion layers separated by a layer ofwater insoluble colloidal material soluble in aqueous organic solventmedia or alkaline solution. Other objects will appear hereinafter.

Our invention will now be described with particular reference to theaccompanying drawings in which Fig. 1 represents a magnifiedcrosssection of a film of the simplified form of our invention, and

Fig. 2 represents a magnified cross-section of a film of morecomplicated structure embodying our invention.

Various examples and equivalents will be described.

As shown in Fig. 1, a film of the simplified form of our inventionconsists of a support In carrying on one side a red sensiitve emulsionlayer H and a green sensitive emulsion layer l3 separated by a strippinglayer 12 of a water solu-' ble or permeable cellulos ester. A strippingfilm of this type may be prepared as described in the following example.

Example 1 halation layer and an antistatic layer (not.

shown) on its rear surface, is first coated with a red sensitiveemulsion layer ll. Over the emulsion layer is coated a stripping layerI! of a water soluble cellulose ester such as cellulose acetate,preferably of an acetyl content of approximately 17 per cent. The layerof water soluble cellulose ester is coated from a 1 per cent solution ofthe ester in water. Over the water soluble cellulose ester strippinglayer may be coated a layer 83 of green sensitive emulsion. If desired,the cellulose ester film support may consist of other esters ofcellulose besides cellulose nitrate, for instance,

cellulose acetate, mixed esters of cellulose such be used. Celluloseacetate of that range of acyl content is particularly useful. Ifdesired, a surface active agent such as saponin may be used in coatingthe water soluble stripping layer.

The order of arrangement of the sensitive layers in the film is notcritical, that is, in an alternative arrangement the outermost emulsionlayer may be blue sensitive and the inner emulsion layer red or greensensitive, the particular arrangement being that chosen for the processin use.

As shown in Fig. 2 of the accompanying drawing, a stripping filmconstructed according to the more complicated manner of our inventionhas a cellulose ester film support l0, preferably of cellulose nitrate,coated with a red sensitive emulsion layer 1 I, a cellulose esterstripping layer ll of a cellulose ester soluble in aqueous organicsolvent or soluble in alkaline solutions, but insoluble in water, agreen sensitive silver halide emulsion layer I3, a water solublecellulose ester stripping layer it, a yellow filter layer ll, andoutermost. a blue sensitive silver halide emulsion layer II. If desired,a magenta filter layer may be placed between emulsion layers ii and ii.A film of this type may be prepared as described in the followingexample:

Example 2 A cellulose nitrate or other cellulose ester film support itprovided on its rear surface with antihalation and antistatic layers isfirst coated with a layer ii of red sensitive silver halide emulsion.Over this layer is coated a very thin layer H of a cellulose ester, suchas cellulose acetate, soluble in a mixture of water and alcohol such ascellulose acetate of approximately 19 per cent acetyl. from a coatingsolution containing 1 per cent of the cellulose acetate in a mixture of30 parts of ethyl alcohol, 30 parts of methyl Cellosolve and 39 parts ofwater. In an alternate formula the cellulose acetate may be coated froma solution of equal parts of acetone and water. Over the thin layer H ofcellulose acetate is then coated a green sensitive emulsion layer i3,and following this, a layer I! of water soluble cellulose ester, such ascellulose acetate of an acetyl content of approximately 17 per cent,from a 1 per cent solution of the cellulose acetate in water. Over thewater soluble cellulose ester stripping layer is then coated a yellowgelatin filter layer I! followed by a layer of blue sensitive silverhalide emulsion IS.

The dye of the filter layer I! may, for instance, be a pyrrolepolymethine dye of the type disclosed in Brooker and Sprague U. 8.Patent 2,298,731, granted October 13, 1942 as for example, (3-ethyl-2-benzoxazole) -(1-lauryl 2,5 dimethyl-B- pyrrole)-dimethinecyanine iodide or a dye of this type in which the alkyl group in the3-position is selected from the range of decyl to octadeoyl. Also usefulare aldehyde-azo dyes, as for instance, those disclosed in Mannes et al.U. 8. Patent No. 2,078,398 granted April 27, 1937, and other removabledyes.

As mentioned in Example 1, the cellulose ester of the water solublestripping layer separating the green and blue sensitive emulsion layersmay consist, in general, of cellulose esters of a range of acyl contentof from approximately 13 per cent to approximately 19 per cent, andcellulose acetates of this range of acyl content are especially good.For the aqueous organic solvent soluble stripping layer separating thered and vgreen sensitive emulsion layers, in addition to the specificcellulose ester mentioned, one may use other cellulose esters such ascellulose propionate or mixed esters of cellulose such as celluloseacetate propionate and cellulose acetate butyrate, etc., of a range ofacyl content from approximately 19 per cent to approximately 33 percent.

By referring to Figs. 1 and 2 of the accompanying drawing, it is nowapparent how the films constructed in the manner described in thepreceding examples would be used. In order to strip the emulsion layersof the film shown in Fig. 1, it is only necessary to subject theemulsion side of the film to the action of water in order to cause aseparation to occur between emulsion layers II and H. In a similarmanner, the film shown in Fig. 2 and constructed as above described inExample 2 may be treated with water on the emulsion side to cause aseparation to occur between the green and blue sensitive emulsionlayers, and when the blue sensitive emulsion layer has been strippedfrom the fil y application of a dilute alcohol solution, as for example,or the lower alcohols such as methyl or ethyl alcohols, the celluloseester stripping layer i4 is softened and the green sensitive emulsionlayer I! may be stripped from the red sensitive emulsion layer il.

It has also been found that it is possible to strip the emulsion layersof the film shown in Fig. 2 by the sole application of water. That is,the outer emulsion layer i8 strips readily after the film has beenwetted with water for a suitable length of time, and the green sensitiveemulsion layer 13 remains bonded to emulsion layer Ii by means ofstripping layer it. If the remaining film carrying emulsion layes I land i3 is again treated with water for a suitable length of time it isfound that the green sensitive emulsion layer may be stripped away fromemulsion layer Ii. This latter stripping action differs from the actionobserved when an aqueous organic solvent solution is used, in therespect that when water is used the adhesive bond between the emulsionlayer and the stripping layer I4 is merely destroyed, whereas, when anaqueous solvent medium is used the stripping layer ll is partially orcompletely dissolved allowing separation of the layers to occur.

In general, complete solution 01' the layer is not achieved nor is itdesirable during the stripping operation. While the stripping layer isof a material that may be completely soluble in water, use is not madeof this property. The film is wetted or moistened only to the extentnecessary to destroy the slight adhesive bond, between the outeremulsion layer and the stripping layer; or

to render this bond less than the bond between the outer emulsion layerand the new support layer which is applied to it.

In an alternative method a film of the type described in Example 2 andalso illustrated in Fig. 2 of the accompanying drawing, may be preparedas described in the following example.

Example 3 In the manner described in Example 2, after the film supportit) has been provided with the red sensitive emulsion layer II, a layeris of alkali soluble but water insoluble cellulose ester is coated.Suitable for this purpose is a cellulose dicarboxylic acid ester ofsuitable viscosity, such as cellulose acetate phthalate of a phthalylcontent of at least approximately 15 per cent and of suitable viscosity.A suitable composition for coating cellulose acetate phthalate of thistype is 1 to 5 per cent of the cellulose ester in equal parts of methylalcohol and acetone. Alternately, the ester may be coated in similarconcentration from a mixture of 20 parts or water, 20 parts of methylCellosolve and 60 parts of acetone. After coating this layer theremaining layers may be coated as described in Example 2. The film soconstructed is treated on the emulsion side with water in order toseparate the blue sensitive emulsion layer from the remainder of thefilm, however, in order to separate the red and green sensitlve emulsionlayers after the blue sensitive emulsion layer has been removed, thefilm is treated with a dilute solution of alkali.

In a specific procedure alternative to that described in Example 2, thelayer corresponding to layer I 4 of Fig. 2 may be composed of celluloseacetate propionate 9-10 per cent acetyl and 13-14 per cent propionyl,and layer 12 of cellulose acetate propionate 7-8 per cent acetyl and11-12 per cent propionyl. Similarly, in the process described in Example2, the cellulose ester for layer I4 may consist of a mixture of watersoluble and water insoluble varieties of hydrolyzed cellulose esters,such as cellulose acetate. Likewise, the layer may consist of a mixtureof various proportions of the lower and higher acyl esters of celluloseof the water insoluble type, such as cellulose acetates.

The stripping films of our invention may be used in the imbibitionprocess of motion picture color photography as more fully described inthe copending U. S. patent application Serial No. 453,959, filedconcurrently herewith by Capstaff, one of the present applicants.

In addition to the alkali soluble but water insoluble cellulose estersabove-mentioned as useful in stripping layers which are designed to besoftened or dissolved in dilute alkaline solutions, we may use alkalisoluble, derivatives of cellulose such as oxidized cellulose describedin Yackel et al. U. S. Patent 2,232,990, granted February 24, 1941, andoxidized cellulose esters insoluble in water but soluble in alkalinesolutions, such as those described in Kenyon et a1. U. S. patentapplication, Serial No. 380,164, filed February 24. 1941, and Fordyce U.S. patent ap plication, Serial No. 347,198, filed July 24, 1940.

We also consider as within our invention the use of both strippinglayers, in the form comprising three difierentially color sensitivelayers, of the same cellulose derivatives such as are above described.These may l be utilized in a process wherein dependence is placed on thecontrol of the wetting baths whereby the first emulsion is stripped whenthe first stripping layer has been sufiiciently affected to permit readystripping but before the water has permeated to the second strippinglayer.

The wetting time must be carefully controlled with the two difierenttypes of interlayer. This control is of vital importance as is also thebonding time.

It is to be understood that the disclosure herein is by way of exampleand that we consider as included in our invention all modifications andequivalents falling within the scope of the appended claims.

What we claim is:

1. A photographic stripping film comprising a support having on one sidetwo superposed silver halide emulsion layers separated by a layer ofcellulose ester of an acyl content of from approximately 13 toapproximately 19 per cent.

2. A photographic stripping film comprising a support having on one sidetwo superposed silver halide emulsion layers separated by a layer ofcellulose acetate, the acetyl content of which is of the order of 17 percent.

3. A photographic stripping film comprising a support having on one sidethereof three differentially colored sensitized emulsion layers andstripping layers between the successive sensitive layers, one of saidstripping layers comprising a water soluble cellulose ester and theother strip ping layer comprising a cellulose derivative insoluble inwater and selected from the group comprising cellulose esters soluble inaqueous organic solvent media and cellulose derivatives soluble inalkaline solutions. A

4. A photographic stripping film comprising a support having on one sidethree superposed silver halide emulsion layers, the outer two emulsionlayers separated by a layer of cellulose ester soluble in water, theinner two emulsion layers separated by a layer of water insolublecellulose derivative selected from the group consisting of celluloseesters soluble in aqueous organic solvent media and cellulosederivatives soluble in alkaline solution.

5. A photographic stripping film comprising a support having on one sidethree superposed silver halide emulsion layers, the outer two emulsionlayers separated by a layer of cellulose ester soluble in water, theinner two emulsion layers separated by a layer of water insolublecellulose ester soluble in aqueous organic solvent media.

6. A photographic stripping film comprising a] support having on oneside three superposed silver halide emulsion layers, the outer twoemulsion layers separated by a layer of cellulose ester soluble inwater, the inner two emulsion 1 layers separated by a layer of waterinsoluble soluble cellulose acetate containing approximately 19 per centacetyl.

8. A photographic stripping film comprising a support having on one sidethree superposed silver halide emulsion layers, the outer two emulsionlayers separated by a layer of cellulose ester soluble in water, theinner two emulsion layers separated by a layer of water insolublecellulose derivative soluble in alkaline solution.

9. A photographic stripping film comprising a support having on one sidethree superposed silver halide emulsion layers, the outer two emulsionlayers separated by a layer of cellulose ester soluble in water, theinner two emulsion layers separated by a layer of water insolublecellulose dicarboxylic acid ester soluble in alkaline solution.

10. A photographic stripping film comprising a support having on oneside three superposed silver halide emulsion layers, the outer twoemulsion layers separated by a layer of cellulose ester of approximately17 per cent acetyl, the inner two emulsion layers separated by a layerof water insoluble cellulose dicarboxylic acid ester soluble in alkalinesolution.

JOHN G. CAPSTAFF; GALE F. NADEAU. CLEMENS B. STARCK.

